There is considerable confusion regarding the difference between a visa and an individual's nonimmigrant status in the U.S. In everyday conversation the term "visa" is often used incorrectly to refer to an individual's legal immigration status. In reality both terms have very specific legal definitions. It is important to remember the distinction between the two terms.
Visa Vs Immigration Status
A visa is an official travel document issued by a consulate overseas allowing a foreign national to apply for admission into the United States. The visa is computerized document with the picture of the foreign national. See sample visa. There are many types of visas issued by the United States, each corresponding to a specific immigration classification and purpose for being in the U.S.. Reciprocity agreements between the U.S. and each individual country govern the cost of the visa, how long it is valid and how many times an individual can use it to apply for entry into the U.S. Having a visa in the passport is not an automatic guarantee that a foreign national will be admitted into the U.S. in that status. A visa is like an invitation that allows an individual to apply for admission into the U.S. in a particular immigration status. Without the right visa, an individual will not be admitted in that status. Even with a visa in the passport, the foreign national may still need to establish his/her legitimate reasons for entering the United States when he/she applies for admission to the country.
NOTE: Canadian citizens are exempt from having to obtain a visa in their passport for entry into the U.S.
Once a foreign national is legally admitted to the U.S., the visa ceases to be an important document. It does not become important again until the foreign national leaves the country and wishes to return. Upon entry into the U.S., the Form I-94 governs an individual's legal immigration status and its duration.
Immigration status is the classification the U.S. Citizenship and Immigration Services gives foreign nationals when they are admitted into the U.S. (B-1, B-2, F-1, J-1, H-1B, etc.). This status corresponds to the primary purpose for coming to the U.S. The status is written on the I-94 card which is given to them upon entry into the U.S.. Under certain circumstances, a foreign national may apply for a change of status within the United States.
Unfortunately, this card does not look as important at the visa. Sample I-94 card. As a result, many offices (banks, drivers license administrators, land lords, etc.) get confused.